A mobile wireless communication system generally uses a plurality of antennas so as to increase a reception gain by improving the reception performance at a base station and a mobile terminal station. Here, there is a fading as one of factors which cause deterioration of the reception performance. The fading is a phenomenon in which a radio signal transmitted from the base station or the mobile terminal station turns into multipath signals arriving through a number of paths due to reflection, refraction and scattering by buildings, vehicles, trees and the like existent between both stations. When such multipath fading occurs, the received power fluctuates at a reception antenna end. Thus, it has been adopted a countermeasure to reduce influence of the multipath fading by preparing a plurality of antennas at a reception side so as to increase received power.
FIG. 7 is a functional block diagram illustrating a schematic configuration of a main part of a conventional wireless communication apparatus reducing the influence of such multipath fading to increase a reception gain. The wireless communication apparatus is provided with a plurality of antennas 101-1 to 101-M. Arrival signals received by the antennas 101-1 to 101-M are reception-processed and an A/D-converted by corresponding reception units 102-1 to 102-M. Output signals from theses reception units 102-1 to 102-M are diversity-combined so as to maximize combined received power by a combining circuit 103, and the combined reception signal thus generated are equalized by an equalizer 104 and then error-corrected and decoded by a decode circuit 105.
As a method of combining a plurality of reception signals by the combining circuit 103, it is known, for example, by use of a known information signal inserted in the reception signals, to calculate antenna weight for each antenna minimizing an error of the phase of the known information signal received based on MMSE (Minimum Mean Square Error), correct the phase of the reception signal from each reception unit based on the antenna weight calculated, and combine the reception signals to obtain a combined reception signal having a sufficiently high SNR (Signal to Noise Ratio) (for example, see Patent Document 1).
In the conventional wireless communication apparatus shown in FIG. 7, the combining circuit 103 performs a primary equalizing process to correct the phase of each reception signal as a preprocessing for combining reception signals from reception units. Then, the equalizer 104 performs a secondary equalizing process on a combined reception signal based on the amplitude of the known information signal. In addition, the decoder circuit 105 performs error correction on the combined reception signal using reliability information (combined power), which is generated in the secondary equalizing process of the combined reception signal by the equalizer 104 and decodes the combined reception signal, and then outputs a result. Such a method for error correction using reliability information is disclosed in Patent Document 2, for example.    Patent Document 1: JP 2003-501971 T    Patent Document 2: WO 2004/082182